There’s no doubt that the Keio Synthesizer Traveler is the most bizarre pedal in the list of Vintage Japanese Fuzzes you should know, which appeared in a Gear feature on Reverb. You can read it here
The unit is bigger than some studio apartments and features a white rubber treadle and nifty aluminum housing. It’s genuinely unclear as to what Keio was trying to accomplish; the knobs are labeled Singing, Fuzz, Traveler and Peak. There are two footswitches, Fuzz and Singing. The “Singing” feature is actually an ear-piercing oscillator, whose pitch is controlled by the position of the foot pedal. All four knobs to the right are actually mix controls for the various features, so if players so desire, they can have fuzz, oscillation and filter sweeping (and whatever “Traveler” is) all going full blast at the same time. It’s also worth mentioning that Keio was the brand name of Korg before Korg was a multi-national corporation with its fingers in guitar and synth gear.
I have had this particular unit for about 14-15 years, it is in exceptional condition and unlike any other you will find on the market it has the original box and manual.